Azide-PEG6-Tos

This Azide-PEG6-Tos linker is designed for modular PROTAC synthesis, providing a flexible polyethylene glycol spacer that can improve conjugation efficiency and tune the spatial relationship between ligands. The tosylate leaving group enables reliable functionalization, while the terminal azide handle supports orthogonal click chemistry for late-stage assembly. Its combination of reactivity and conformational flexibility makes it well suited for building targeted protein degraders, as detailed in the sections below.

Structure: The linker comprises a PEG-based polyether chain terminating in an azide functionality and a tosylate (tosyl) group. It contains ether linkages within the PEG segment, an aryl sulfonate ester at the tosyl end, and an azide substituent. These features confer aqueous compatibility and chemical stability under standard organic handling.

Reactivity: The tosylate moiety is suitable for nucleophilic substitution reactions, enabling installation of amine or other nucleophiles under base-promoted conditions. The azide group supports copper-catalyzed azide–alkyne cycloaddition or strain-promoted azide–alkene/alkyne click strategies for orthogonal coupling. Typical workflows use polar aprotic solvents and mild bases, with careful control of moisture and oxygen to preserve azide integrity and maintain chemoselectivity.